Fuel pump for internal-combustion engines



. I June 2, 1953 J, MAL|N 2,640,422

FUEL PUMP FOR INTERNALCOMBiJSTION ENGINES I Original Filed Dec. 3, 1,046

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JAY B. MALI/v ATTdENE'Y-S June 2, 1953 J. B. MALIN FUEL PUMP FOR INTERNAL-COMBUSTION ENGINES Original Filed Dec. 3, 1946 2 Sheets-Sheet 2 y 33 K ma A INVENTOR. JAYJB. MAL/N EM WM.

' ATTORNEYS Patented June 2, 1953 UNITED STATES PATENT OFFICE FUEL PUMP FOR INTERNAL-COMBUSTION ENGINES tion of Delaware Original application December 3, 1946, Serial No.

Dividedand this application Novemher 6, 1947, Serial No. 784,462

2 Claims. 1

This invention relates to a fuel pump for an internal combustion engine operating with fuel injection and having a plurality of injection nozzles for each cylinder, wherein the number of nozzles of a cylinder which are in operation per cycle depends upon engine load.

This is a division of my copending application Serial No. 713,791, filed December 3, 1946, now Patent No. 2,506,538, dated August 12, 1952.

Diesel engines have heretofore been proposed having plural nozzles for each cylinder Which come into operation successively on each cycle, wherein the number of nozzles per cylinder in service .per cycle varies with load, and all nozzles in service have the same cutoff or termination of injection in the cycle. The present invention is distinguished by the fact that all the nozzles per cylinder in service per cycle have the same injection advance, and also by the fact that the low load or idling nozzle is maintained at full duration and capacity on each cycle at a higher load range, while a higher load nozzle has a variable cutoff in accordance with load within the higher load range.

Fuel-injection spark-ignition engines have alsobeen proposed, wherein a single fuel injectionnozzle having a plurality of fuel ports is regulated by a sliding sleeve interconnected with the throttle control so that the number of jets and spacial distribution of the injected fuel per cycle vary with load. The present invention is distin-- guished by the fact that each cylinder has a plurality of nozzles supplied by separate pump plungers, together with a fixed cutoff of the low load nozzle and a variable cutoif of a higher load nozzlev within the higher load range,

In the copending application of Everett M. Barber, Serial No. 10,598, filed February 25, 1948 now Patent No. 2,484,009, dated October 11, 1949,

said application being a continuation-in-part of Serial No. 513,232, filed December 7, 1943, the latter now abandoned, there isd-isclosed and claimed a fuel-injection spark-ignition. engine, wherein fuel is injected into swirling compressed air in the cylinder combustion space toward the latter part of the compression stroke, the first i-n-* crement of injected fuel is spark-ignited substantially as soon as combustible fuel Vapor-air mixture is formed therefrom to establish a flame front, and the injection of fuel is continued into 1 the swirling compressed air immediately inad-- Vance of the fi-ame front to progressively form additional combustible fuel vapor-air mixtureswhich are ignitedby the flame front and burned substantially as rapidly as formed, and knocking 2 of the engine is prevented. in a specific embodiment disclosed and claimed therein, fuel is injected tangentially into the combustion space in the direction of air swirl, and spark ignition of the first increment of injected fuel i secured by a spark plug mounted adjacent the injection no'zzle, with its electrodes positioned at an edge of the spray form adjacent the peripheryof the combustion space and in the region of diffusing fuel vapor-air mixture first produced therefrom.

The present invention is particularly applicable to an engine of this non -knockin type, especially one having large diameter cylinders.

At part load operation (if an engine having swirling air and a stratified charge produced by injecting fuel into a localized portion of that swirling air, an opportunity is resented for the fringes of the stratified charge, or fuel cloud, to become dissipated by mixing with the surrounding swirling air so as to form an incombustibly lean mixture; The fuel thus lost becomes a greater percentage of the total charge when (1) the time interval between injection and ignition is increased, (2) the total charge is" decreased for part load operation with a plurality of nozzles, and (3) when the surface to volume ratio of the fuel patch or cloud is increased.

In accordance with thepresent invention, a fuel pump is provided which enables an engine cylinder having two or more fuel injectors to be operated at part throttle by cutting out one or more of the injectors and having in service the minimum number of injectors operating at their most efficient capacity to provide the proper fuelair ratio of the localized or stratified charge; This minimizes the effects of (2')" and (3) listed above, and enables the injector or injectors remaining in service per cycle to function at their most economical fuel consumption level. Experimental work on a large diameter cylinder havas for. spark ignition engines, and particularly those of: the stratified charge type.

Where the invention is applied to a non-knocking engine wherein spark ignition occurs promptly after the start of' fuel injection, the effect of the time e1ement' of (1)' aboveis substantially eliminated. Moreover, by confining the calized charge to that produced from a single nozzle at low load or idling, the surface to volume ratio of the fuel patch is maintained much less than is produced by the injection of the same amount of fuel from two or more spaced nozzles. This minimizes the effect of item (3) above. The net result is more eflicient part load operation with substantial fuel economy.

It is therefore a principal object of the present invention to provide a novel fuel pump for operating an injection engine having two or more injectors per cylinder at the most economical fuel consumption level.

Another object of the present invention is to provide a fuel pump supplying plural injectors for each cylinder with the same injection ad- Vance, and wherein the number of injectors operating per cycle decreases with load, while any remaining injector in service continues to function at a higher rate, affording more efficient part load operation.

Still another object of the present invention is to provide a novel fuel pump for an engine of the foregoing character, which pump is simple and sturdy in construction, reliable in operation, readily controlled from the customary throttle, and capable of being driven from the usual engine cam shaft.

Other objects and advantages of the present invention will be apparent from the following description when taken in conjunction with the attached drawing and appended claims.

In the drawing, which discloses a preferred embodiment of the invention:

Fig. 1 is a vertical sectional view of an engine cylinder taken on the plane of the line |-l of Fig. 2, together with the fuel pump partly in elevation and partly in section to illustrate the construction thereof;

Fig. 2 is a horizontal sectional view looking upwardly on the cylinder head and taken on the plane of line 22 of Fig. 1;

Fig. 3 is an enlarged perspective View of two cooperating pump plungers of the fuel pump, with their cylinders partially broken away and in section, and also illustrating the rack control;

Figs. 4-7, inclusive, are diagrammatic views of the engine combustion space illustrating the beginning and end of injection for approximately half load and full load operation, respectively; and

Fig. 8 is a diagram plotting total quantity of fuel injected per cycle against the injection duration or pump plunger rotation, illustrating the quantity of fuel supplied by the two nozzles per cycle at different engine loads.

Referring to Figs. 1 and 2, the engine cylinder is indicated at H] with water jacket H, piston I2 and connecting rod [3 which runs to the usual crank shaft, not shown. The cylinder head 14 is formed with an air inlet port controlled by an intake valve I 6 and a similar exhaust port controlled by an exhaust valve 17. The intake valve is equipped with a shroud l8 which is set tangentially so that, on the suction stroke of piston l2, air is drawn into the disc-shaped combustion space [9 in a manner to impart a swirling movement of high velocity to this air within the combustion space, as indicated by the arrow 20. This high velocity air swirl is maintained during the compression stroke of piston 12.

Mounted in the cylinder wall and directed generally tangentially of the combustion space 19, are a low load nozzle 22 and a high load noz le 23. Carried by the cylinder head is a spark plug 24 positioned on the air downstream side of nozzle 22 at a central angular distance of about 20-90 and, preferably, about 30-60", as indicated by the arrow 25 (Fig. 2). The electrodes 26 of spark plug 24 are positioned slightly below the inner surface of the cylinder head and arranged so as to be closely adjacent the upper side of the fuel jet 2! from nozzle 22. The arrangement is such that the electrodes 26 are out of the direct path of atomized liquid fuel particles, but are positioned so as to be contacted by the combustible fuel vapor-air mixture rapidly formed at the edge of the spray and diffusing away therefrom.

A similar spark plug 28 is mounted in the cylinder head in a similar position with respect to the spray form 29 from nozzle 23. It will be noted that nozzles 22 and 23 are arranged at diametrically opposite sides of the cylinder and have their respective spray forms arranged to uniformly impregnate the air on opposite sides of the combustion space as it swirls past said nozzles.

Spark plugs 24 and 2B are also arranged diametrically opposite each other and, as shown in Fig. 2, are positioned about intermediate between the center of the combustion space and the periphery thereof. However, it should be pointed out that the spark plugs can be located in any suitable positions with their electrodes closely adjacent the edges of the respective spray forms so as to contact combustible fuel vapor-air mixtures substantially as soon as formed from the first increments of injected fuel from the nozzles 22 and 23, respectively. For example, plugs 24 and 28 can also be carried in the cylinder wall with their electrodes adjacent the periphery of the combustion space and along the outer edges of the spray forms 2'! and 29.

As shown diagrammatically in Fig. 1, leads 30 and 3| are respectively connected to contacts 32 and 33, which are simultaneously contacted by a suitable rotary distributor 34 driven in synchronism with the engine. Lead 30 extends to spark plug 24 and lead3| to spark plug 28. It will be understood that the distributor 34 is part of a conventional ignition system, including lead 36, whereby the timing of spark ignition can be correlated and synchronized with the timing of fuel injection on each cycle. In this manner sparks of igniting intensity are present simultaneously at the electrodes of plugs 24 and 28 on each cycle, usually about 4 to 10 crank-angle degrees following the start of fuel injection, at which time combustible fuel vapor-air mixture from the first increment of injected fuel from each of nozzles 22 and 23 reaches the electrodes at higher engine loads. At lower engine loads or idling, nozzle 23 is cut out, and fuel is injected only from nozzle 22 on each cycle. If desired, plug 28 can also be cut out when nozzle 23 is idle; but this is not necessary and both plugs can continuously remain in service at all engine loads.

In accordance with the present invention, nozzle 22 functions to supply the entire quantity of injected fuel on each cycle from idling up to approximately half load. At higher loads above approximately half load, nozzle 23 also comes into play. Both nozzles 22 and 23 have the same injection advance so that they both start fuel injection simultaneously at the higher loads, such as about 75 to 30 before top dead center of the compression stroke of piston l2. Nozzle 22 serves to vary the quantity of fuel injected on trated in Fig. 3. In this position, plunger 55 supplies the total quantity of fuel injected per cycle. Moreover, that plunger is delivering just short of its maximum capacity, or has just less than its maximum duration of delivering fuel under injection pressure to nozzle 22. Further adjusting movement of rack bar toward the left by means of the throttle control in response to increasing load simultaneously rotates plungers 55 and 55 counter-clockwise, thereby progressively increasing the delivery of fuel by plunger 55 to its maximum at the point 8 I. This is reached when the lower end of helix l0 rotates into registration with the bottom of port 64, so that the lower horizontal surface H at the upper end of annular fuel chamber 66 then controls the point of cutoff of pumping unit 42. At this point of rotative adjustment, the upper edge of helix 10' of pumping unit 43 is just brought into registration with port 64. The length of the vertical edge 68 is just greater than the diameter of port 64, so that plunger 55 then has a very short pumping period during which fuel under injection pressure is supplied to nozzle 23. In that position, only a small amount of fuel is injected per cycle from nozzle 23, while nozzle 22 delivers its maximum quantity. This is illustrated in Fig. 8 by a position just above point 8|.

Further rotative movement of plungers 55 and 55' in counter-clockwise direction for increasing load within the upper load range brings a different part of the horizontal surface H of plunger 55 opposite port 66, so that this pumping unit 42 remains at maximum capacity and duration. At the same time, the helix ID of plunger 55 is now in play opposite the port 64'. Thus the amount of fuel under injection pressure delivered by plunger 55' on each cycle progressively increases with increasing load, as indicated by the diagonal line 82 of Fig. 8, while the amount of fuel delivered under injection pressure by plunger 55 remains constant at full capacity as indicated by the horizontal line 83. It will be appreciated that helix ill of plunger 55 is displaced angularly about 90 from the helix T0 of plunger 55. For maximum load, both plungers 55 and 55' are rotated their full extent in a counter-clockwise direction. This leaves the horizontal surface H of plunger 55 still opposite port 64, while a corresponding horizontal surface at the lower end of helix 10' (which is behind plunger 55' as illustrated in Fig. 3), has just moved opposite port 54', so that plunger 55 is now also delivering its full load quantity per cycle, as indicated by the top horizontal line 84 in Fig. 8.

As previously explained, plungers 55 and 55 are driven in unison by identical cams 45 and 46, respectively, carried by cam shaft 44, which latter is driven in conventional manner from the engine at half of the crankshaft speed for four-cycle operation. Consequently, plungers 55 and 55 are always at the same point in their pumping strokes. This means that pumping units 42 and 43 have the same injection advance. During operation from about half load up to full load when both nozzles 22 and 23 are functioning, the injection of fuel is initiated from both nozzles at the same point in the cycle. As the engine load is decreased from full load to about half load, the variation in fuel supply is accomplished by varying the duration of injection from nozzle 23, while nozzle 22 remains at full duration. At about half load, nozzle 23 is cut out entirely; and then further reduction in load is taken care of by varying .the duration and consequently the quantity of fuel injected per cycle from nozzle 22, as indicated by the inclined line of Fig. 8. The net result is that both nozzles 22 and 23 are operated at all times at substantially their most economical level to uniformly impregnate those portions of the compressed air swirling past them during the injection period to take care of the load demands.

The operation of the engine is more particularly illustrated in the diagrammatic views of Figs. 4-7, inclusive. Fig. 4 illustrates the begin ning of injection for just under half-load operation, with a setting of the fuel pump as shown in Fig. 3, and indicated by the horizontal line 80 of Fig. 8. At this setting nozzle 22 is in service, while nozzle 23 remains idle. At about '70 to 30 before top dead center, the injection of fuel is initiated by jet 2! from nozzle 22. About 4-10 crank angle degrees thereafter, combustible fuel vapor-air mixture from the upper edge of the first increment of injected fuel has reached the electrodes 26 of plug 24, and a spark of igniting intensity is present at said electrodes at this time to initiate combustion and establish a flame front across the path of the swirling air, as indicated at 81.

Fig. 5 indicates the same cycle at substantially the end of fuel injection, which may have a duration of about 30 to- 70 for maximum delivery of one nozzle 22 shown in operation. It will be appreciated that following ignition and establishment of the frame front 81, as illustrated in Fig. 4, the injection of fuel is continued from nozzle 22 immediately in advance of the flame front so that additional increments of combustible fuel vapor-air mixture are progressively formed and burned substantially as rapidly as produced. The resulting products of combustion are carried by the swirling mass beyond the flame front, and these products substantially fill the combustion space between the flame front 81 and the locus of nozzle 23, as indicated by the numeral 88 in Fig. 5.

Fig. 6 illustrates the beginning of injection for substantially full load operation. Fuel is simultaneously injected at the same point in the cycle from both nozzles 22 and 23 in jets 21 and 29, respectively, at diametrically opposite sides of the combustion space. Combustible mixtures formed from the first increments of injected fuel from both nozzles 22 and 23 are simultaneously ignited by plugs 24 and 28 to establish the two flame fronts 81 and 89 at the opposite sides of the combustion space. Fuel injection is continued from both nozzles 22 and 23 immediately in advance of the respective flame fronts 81 and 89, while products of combustion are swept beyond the flame fronts. Consequently, at the termination of injection for full load, illustrated in Fig. '7, the products of combustion 88 formed by the progressive burning of combustible mixture produced by fuel injection from nozzle 22, and the products of combustion 90 formed by the progressive burning of combustible mixture produced by fuel injection from nozzle 23, substantially fill the entire combustion space, with the exception of the remaining localized portions of swirling air which are at that instant being impregnated by the final increments of injected fuel occupied by jets 21 and 29.

While in the specific embodiment described above, two nozzles are provided for each cylinder, located at diametrically opposite sides, together with a fuel pump having two pump cylinders for each engine cylinder, it will be understood that the present invention is applicable to a larger number of nozzles per cylinder. For example, three nozzles per cylinder may be provided located approximately 120 from each other. In this case, it will be understood that the fuel pump is equipped with three cooperating pumping units per engine cylinder, and the helices are offset angularly of the pump plungers so as to bring the nozzles into operation in accordance with load, but with the same injection advance, in the manner previously described. Generally, it will be unnecessary to provide more than three nozzles per cylinder, even for the largest diameter cylinders. Moreover, for most cylinders of medium large size, the construction illustrated with two nozzles is preferred.

While the invention has been described above as applied to a non-knocking engine of the character in which ignition occurs immediately after the start of injection, it is to be understood that the invention is useful in connection with other types of engines. For example, the invention can advantageously be employed in a stratified charge engine of the character of the Hesselman. engine employing swirling air, but in which injection is complete, or substantially complete, at the time ignition occurs. In fact, the invention is particularly useful in such. an engine, since there is a longer period of time on each cycle for dissipation of fuel from the fringes of the Stratified charge before ignition occurs. The in vention is also useful in connection with a diesel engine operating with compression ignition, particularly an air-swirl diesel, as well as semi-diesels operating with glow plugs and the like.

Obviously many modifications and variations of the invention as hereinbefore set forth, may be made without departing from the spirit and scope thereof and, therefore, only such limitations should be imposed as are indicated in the appended claims.

What I claim is:

1. A fuel pump comprising a pair of cooperating pump cylinders, each pump cylinder having a pump plunger reciprocatingly and rotatively mounted therein, separate fuel inlets for supplying fuel to each of said cylinders, the latter having separate discharge chambers provided with separate offtakes, said cylinders also having separate fuel by-pass ports, means for reciprocating said plungers in unison on their pumping strokes at all loads to provide the same injection advance, a common rack bar meshing with rack gears operatively connected to said plungers for rotating said plungers in unison, a helix on each plunger for regulating the amount of fuel delivered by each plunger on its pumping stroke to its respective discharge chamber and for controlling communication of the fuel inlet with the by-pass port to terminate delivery on each cycle, the said helices having substantially the same slope and length with the helix on one plunger being ofiset angularly from the helix on the other plunger by an angular extent substantially equal to that of a helix so as to become operative in succession as the rack bar is moved to rotate said plungers throughout their range of rotative movement, the fuel channel of one of said plungers being of extended angular extent substantially equivalent to the angular 7 extent of a helix in comparison to the angular extent of the fuel channel of said other plunger to maintain the fuel inlet controlled by said one plunger in communication with the by-pass port during the range of simultaneous rotative movement of both plungers wherein the helix of said other plunger is shifted from zero to maximum discharge positions, the helix on said one plunger then coming into play on further rotative movement of said plungers to regulate and vary the discharge from its pump cylinder on each cycle while the discharge from the other pump cylinder remains at maximum amount.

2. Fuel feeding mechanism for a single cylinder of an internal combustion engine, comprising a plurality of cooperative pump cylinders, each having a separate discharge chamber provided with an offtake, a separate fuel inlet and a separate by-pass port, separate pump plungers for each of said pump cylinders, each pump plunger being reciprocatingly and rotatively mounted in its respective cylinder, means for reciprocating said plungers in unison on their pumping strokes to provide the same injection advance, a common load control means for rotating said plungers in unison throughout their range of rotative movement, a helix on each plunger for regulating the amount of fuel delivered by each plunger on its pumping stroke to its respective discharge chamber and for controlling communication of the fuel inlet with the by-pass port of its pump cylinder through a cooperating fuel channel to terminate delivery on each cycle, the said helices having substantially the same slope and length with the helix on one plunger being ofiset angularly from the helix on another plunger by an angular extent substantially equal to that of a helix so as to become operative in succession as said common load control means is actuated to rotate said plungers, the fuel channel of said one plunger being of expanded angular extent substantially equivalent to the angular extent of a helix relative to the angular extent of the fuel channel of another plunger to maintain the fuel inlet controlled by said one plunger in communication with its by-pass port during the range of simultaneous rotative movement of both plungers wherein the helix of said other plunger is shifted from zero to maximum discharge positions, the helix of said one plunger then coming into play on further rotative movement of said plungers to regulate and vary the discharge from its pump cylinder on each cycle while the discharge from said other pump cylinder remains at maximum amount.

JAY B. MALIN.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 845,140 Stuart Feb. 26, 1907 1,239,523 Rogers Sept. 11, 1917 1,967,101 Rassbach et al July 1'7, 1934 2,001,843 Kasley May 21, 1935 2,298,936 Gambrell Oct. 13, 1942 FOREIGN PATENTS Number Country Date 241,494 Great Britain Oct. 22, 1925 340,664 Great Britain Jan. 8, 1931 342,916 Great Britain of 1931 

